B. Protect the athlete from further injury. This is because, if the athlete is injured any further (as in, if someone bumps into him or they put any pressure on the injury) he can get a more serious or permanent injury because of it. So in these situations, they usually surround him, lift him and move him off the field or wait until medical personnel arrives.
Centripetal acceleration is the motion inwards towards the center of a circle. It is given by the square of velocity, divided by the radius of the circular path.
ac = v²/r, where ac is the centripetal acceleration in m/s²
Therefore,
Centripetal acceleration = 3²/20m
= 9/20m
= 0.45 m/s²
Thus, the centripetal acceleration is 0.45 m/s²
Answer:
The speed of the plank is 81.68 m/s
Explanation:
Given that,
Speed of bullet = 152 m/s
Speed of wood = 128 m/s
Speed of another bullet = 97 m/s
We need to calculate the speed of plank
Using conservation of momentum
Where,
u = initial velocity
v = final velocity
....(I)
....(II)
From equation(I) and equation(II)
Hence, The speed of the plank is 81.68 m/s
The answer to ur question is: B
Answer: A. The stone thrown upward spends more time in the air.
Explanation:
The stone thrown above the horizontal has an initial vertical speed, whose direction is opposed to gravity. It means that it decelerate first before accelerating in the direction of gravity. Where the stone thrown below the horizontal has an initial vertical speed in the direction of gravity, so there is no deceleration.
In consequence, the stone thrown upward spends more time in the air. Correct answer is option A.